The present invention relates to fuel injection systems for vehicle engines, and more particularly to common rail gasoline direct injection systems.
The design of the high pressure fuel pump for such common rail direct injection systems requires a number of trade-offs. For example, whereas the maximum required fuel delivery rate while the vehicle is under way can readily be accomplished with a modestly sized pump, the demands for a cold engine start require a delivery rate on the order of three times higher than the maximum needed for travel. As a consequence, conventional pumps are considerably oversized relative to the fuel delivery demands experienced during over 95 per cent of the engine operating time.